The present invention is related basically to skidding carriages and more particularly to self-locking skidding carriages.
It has long been the practice of loggers, when operating in steep terrain, to station a skidding machine at an elevated position adjacent to a landing where logs are loaded onto trucks for transportation to a sawmill. A dragline is either thrown or manually hauled from a winch drum on the skidding machine to the location where trees have been cut. A choker or grapple at the end of the dragline is then fixed about the circumference of a log. The dragline is then retracted toward the skidding machine and the log is dragged along the ground to the landing area.
Another method presently being utilized is a balloon or helicopter hoist type operation wherein a choker or grab at the end of a long cable is connected to a log or logs to be lifted upwardly by the balloon or helicopter and moved to a landing area. Although this is a rather clean operation, it is extremely expensive for the logging contractor.
Another more recent development has been the utilization of skyline skidding wherein a carriage is moved up and down a taut skyline stretched between a boom and a stationary anchor point located downhill from the landing. A dragline is normally carried by the carriage along the skyline down the hill to a position slightly uphill of the anchor point. A person known as a "choker setter" then hauls the dragline and grapple or choker from the carriage to the cut logs. He connects the grapple or choker to a log and signals an operator in the skidding machine. The dragline is then pulled toward the carriage and subsequently towed up the hill with the forward end of the log lifted off the ground with only the tail or downhill end dragging along the ground. This type of operation is not only less detrimental to the environment than conventional skidding, but is relatively inexpensive for the logging contractor to initiate and utilize.
The carriage of the present invention automatically locks at the lower position adjacent the anchor point in order that logs may be pulled toward the carriage from substantially any direction, not necessarily in alignment with the skyline. Further, once the logs have been hauled to the carriage, the locking mechanism is automatically released and the carriage and logs are pulled up the grade to the landing. At the landing, the boom may be lowered or the skyline slackened to lower the logs to the landing and allow the logs to be unhooked from the dragline.